UNIQUE stone age monuments which have been slumbering quietly in the North Yorkshire landscape for 5,000 years have been ‘gifted to the nation’ and will be opened up to the public from today.

The Thornborough Henges, near Ripon, are three giant, circular earthworks, each more than 200 metres in diameter, which are aligned roughly north-south and are part of a Neolithic complex described as the ‘Stonehenge of the North’.

Dating from 3500 to 2500 BC, the henges are thought to have been part of a prehistoric 'ritual landscape' - including a possible timber post avenue, an oval burial monument and several round barrows - which stretches from Ferrybridge to Catterick along a route described as a ‘prehistoric fore-runner to the A1’.

The landscape is said to be comparable with Salisbury Plain in south-west England - and probably the most important single ancient site between Stonehenge and the Orkney Islands in Scotland.

York Press: The two henges which will be open to the publicThe two henges which will be open to the public (Image: Historic England)

Today all three henges are visible as massive circular banks up to four metres high, with encircling ditches. But thousands of years ago, they would have stood on a low promontory overlooking wetlands.

Now, two of the henges - the central and southern ones - have been gifted into the legal ownership of Historic England by sustainable building materials business Tarmac. Lightwater Holdings, a local construction materials provider, has also gifted parts of the monument to Historic England.

They will be managed by English heritage – and from today, they are free for members of the public to visit.

Although they have remained remarkably well preserved over thousands of years, the central and southern henges were added to Historic England’s 'Heritage at Risk' register in 2009 due to historic erosion caused by livestock and rabbits.

Now that they are legally in Historic England’s ownership, they can be better protected - and have been removed from the ‘at risk’ register.

York Press: The Thornborough HengesThe Thornborough Henges (Image: Historic England)

Duncan Wilson, Historic England’s chief executive, said: “Thornborough Henges … are a link to our ancient ancestors, through thousands of years, inspiring a sense of wonder and mystery. We are thrilled to have acquired this highly significant site for the nation, ensuring that these magnificent monuments will be preserved for generations to come.”

Kate Mavor, English Heritage’s chief executive, added: “Thornborough Henges is one of the most important ancient sites in Britain and yet almost completely unknown – we are looking forward to sharing its significance, its stories and its secrets with the public.”

Prime Minister Rishi Sunak, whose Richmond parliamentary constituency includes the henges, said they had 'enormous potential to help tell the story of ancient Britain'.

York Press: Prime Minister Rishi SunakPrime Minister Rishi Sunak (Image: PA)

“Comparatively few people are aware of (the site's) significance – both locally and nationally," he said. "I hope many more will come to appreciate this little-known gem of our history.”

The henges are at West Tanfield in North Yorkshire, postcode DL8 2RA.